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The Short Answer
Ubigi is one of the best eSIMs for Japan— but for a specific reason. It's owned by NTT, the parent of NTT Docomo, so its Japan plans ride Japan's most reliable network directly. You get rock-solid signal in subways, rural areas, and mountains. And there's no longer a price penalty: its 10GB plan ($16.50 for 30 days) costs less than Saily($17.99) or Airalo ($18), both of which run on KDDI and SoftBank in Japan. Nomad is $0.50 cheaper if you don't need Docomo. For most Japan trips, Ubigi is an easy pick.
What Is Ubigi?
Ubigi is a travel eSIM brand operated by Transatel, a Paris-based mobile connectivity company that became a subsidiary of NTT(Nippon Telegraph and Telephone) in 2019. NTT is Japan's largest telecom and one of the biggest in the world. That ownership is the whole story for Japan travel: Ubigi isn't reselling someone else's roaming agreement, it's plugged into the parent company of NTT Docomo.
Founded in 2013, Ubigi predates the current eSIM boom by several years — it started in connected-device and laptop data before pivoting to travelers. The upside is mature carrier relationships and genuinely good network quality. The downside, which we'll get to, is a buying experience that feels a generation behind Airalo and Saily.
Ubigi Japan Plans & Pricing
Ubigi's Japan lineup runs from 1GB to 50GB capped plans, with validity from 3 to 30 days depending on the tier, plus unlimited plans, all on NTT Docomo. Prices below were verified on Ubigi's site in September 2026 and match AvailSim's Japan comparison.
| Data | Validity | Price | Per GB |
|---|---|---|---|
| 1 GB | 3 days | $3.50 | $3.50/GB |
| 1 GB | 30 days | $4.00 | $4.00/GB |
| 3 GB | 15 days | $7.50 | $2.50/GB |
| 5 GB | 15 days | $10.00 | $2.00/GB |
| 10 GB | 7 days | $14.00 | $1.40/GB |
| 10 GB | 30 days | $16.50 | $1.65/GB |
| 25 GB | 30 days | $32.00 | $1.28/GB |
| 50 GB | 30 days | $55.00 | $1.10/GB |
| Unlimited | 8 days | $25.00 | — |
| Unlimited | 15 days | $39.00 | — |
| Unlimited | 30 days | $65.00 | — |
The 30-day option on the 1GB plan is unusually generous — most competitors cap their smallest plans at 3–7 days. For a trip where you mostly use Wi-Fi and just need maps and messaging, the $4 / 1GB 30-day plan is genuinely useful. For heavier use, the per-GB cost drops to $1.65 on the 10GB 30-day plan and $1.10 on the 50GB plan.
The NTT Docomo Advantage
This is the reason to consider Ubigi for Japan over anyone else. Japan has three major networks — NTT Docomo, SoftBank, and KDDI (au) — and Docomo has the broadest coverage, especially in rural areas, subway tunnels, and the mountainous interior. Ubigi routes its Japan plans through Docomo directly, courtesy of the NTT ownership.
In practice that means 40–80 Mbps on 4G/LTE in Tokyo and Osaka, strong signal on the subway, and far fewer dead zones if your itinerary heads into the Japanese Alps, rural Hokkaido, or along the Shinkansen. eSIMs that route through SoftBank or secondary carriers can drop signal in exactly those places.
How to Set Up Ubigi for Japan
Ubigi's setup is standard eSIM, with one quirk: the buying flow is web-first, so don't be surprised if the website is smoother than the app.
Buy before you fly
Purchase your Japan plan on Ubigi's website or app while you're still on home Wi-Fi, ideally 24–48 hours before departure. Ubigi's purchase flow is web-first — the site is often smoother than the app.
Install the eSIM profile
Scan the QR code Ubigi emails you, or install directly through the Ubigi app. On iPhone this lands under Settings → Cellular → Add eSIM; on Android under Settings → Network → SIMs.
Label it and leave data roaming on
Name the line something like "Ubigi Japan" so you can tell it apart from your home SIM. The Ubigi profile needs data roaming enabled to connect to NTT Docomo — that's expected and won't cost extra.
Activate when you land
Your Ubigi Japan plan's validity (3 to 30 days, depending on the plan) starts on first connection. Keep your home SIM set as the data line until you arrive, then switch your data line to Ubigi after landing at Narita, Haneda, or Kansai.
New to eSIMs entirely? Our step-by-step eSIM setup guide walks through iPhone, Samsung, and Pixel in detail.
Ubigi vs Alternatives for Japan
Here's how Ubigi stacks up against the other top Japan eSIMs at the 10GB tier. The pattern is clear: Ubigi is the only one on Docomo and is the second-cheapest of the four with a 10GB plan, Nomad is $0.50 cheaper on KDDI/SoftBank, Saily and Airalo cost slightly more with more polished apps, and Holafly sells only unlimited plans — its 7-day plan ($27.50) costs more than Ubigi's 8-day unlimited plan ($25).
| Provider | Network | 10GB Price | Notes |
|---|---|---|---|
| Ubigi | NTT Docomo | $16.50 | Only one of these on Docomo; direct NTT ownership. |
| Nomad | KDDI / SoftBank | $16.00 | Cheapest of these at 10GB, by $0.50. |
| Saily | KDDI / SoftBank | $17.99 | $1.49 more than Ubigi; more modern app. |
| Airalo | SoftBank / KDDI | $18.00 | Most polished app. |
| Holafly | SoftBank | — | Unlimited only: $11.90 for 3 days, $27.50 for 7 days. |
Want the full side-by-side with live prices across every tier? See the Japan eSIM comparison or the complete Ubigi provider review.
Pros & Cons for Japan
What we like
- Routes through NTT Docomo — Japan's broadest, most reliable network (subways, rural areas, mountains)
- Owned by NTT via Transatel — carrier-grade infrastructure, not a resold MVNO layer
- A 30-day option even at the 1GB tier ($4.00), where most rivals offer 3–7 days
- Hotspot/tethering supported and top-ups available mid-trip
- Priced competitively: 10GB for 30 days is $16.50, below Saily and Airalo
- Unlimited plans on the same Docomo network ($25 for 8 days)
What to weigh
- Not the cheapest everywhere — Nomad is $0.50 less at 10GB, and the 3GB and 5GB plans only last 15 days
- Web-first purchase flow and a dated app vs Airalo or Saily
- Email/portal support only — no 24/7 live chat
- Data-only (no calls/SMS)
The Verdict
Ubigi is the eSIM I'd recommend to two kinds of Japan travelers: anyone heading off the beaten path — rural Hokkaido, the Alps, long Shinkansen legs — where Docomo's coverage edge genuinely matters, and frequent travelers who want one reliable Japan eSIM. Its NTT pedigree is real, not marketing.
For a first-time eSIM buyer on a single Tokyo-and-Kyoto trip, the price question has mostly gone away: Ubigi's 10GB plan ($16.50) is cheaper than Saily's ($17.99) or Airalo's ($18), and among the big-name providers only Nomad ($16) undercuts it. What you give up is a friendlier app — Saily and Airalo are easier to use, on KDDI/SoftBank rather than Docomo. There's no wrong answer here — all of them are good Japan eSIMs.
Compare every Japan eSIM in one place
See live prices from Ubigi, Saily, Airalo, Holafly, and more — filtered by data tier and validity.
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